In the Niagara Peninsula, Ontario, Canada and in other wine grape-growing regions, such as Upper New York State, U.S.A., a significant tonnage of wine grapes of the Labrusca type are harvested which produce a "foxy"flavour when used in wine production. Wines made directly from these grapes have been judged to be inferior to grape wines produced from other grapes which do not impart this flavour.
The flavour is known to result from the presence of certain volatile esters in the wine, mainly methyl anthranilate. The presence of these volatile esters had led to the establishment of a Labrusca Flavour Index (LFI) which is determined by the expression: EQU LFI=100.times.concentration of methyl anthranilate (in ppm)+concentration of total volatile esters (in ppm).
The relative proportions of the various volatile esters present in the grape juice formed from the grapes depends on the variety of grape and the timing of the harvesting of the grape. The total concentration of volatile esters can be in the range of about 200 to about 500 ppm for Labrusca varieties, with later harvesting providing higher concentrations of the volatile esters.
The Labrusca grape has been the predominant wine grape crop of the Niagara Peninsula and the high LFI values of wines produced therefrom has inhibited sales of such wine. Often, a significant proportion of the high LFI wine is blended with low LFI wines, such as, those produced from Vinifera hybrid grapes, to decrease the overall LFI value. In addition, with the increase in recent years of the production of wines from Vinifera grapes and the acceptability of these higher priced wines in the market place, surplus wine production from Labrusca grapes has resulted.
The Labrusca hybrid and French hybrid grapes are now the predominant table wine grapes of the Niagara Peninsula. While many of these varieties contain little or no methyl anthranilate and only minimal levels of total volatile esters, their nature is such that their flavour profile predominates limiting their use in quality table wines.
The following Table I gives typical values of MA and TVE for grapes typically used in making high flavoured wines:
TABLE I ______________________________________ MA TVE Grape (ppm) (ppm) ______________________________________ (a) American varieties Concord 3.37 104 Niagara 2.57 49 Catawba 0.21 43 Delaware 0.33 4 Elvira 0.07 12 (b) Vineland hybrids Ventura 0.02 4 (c) French hybrids De Chaunac 0.01 4 Marechal Foch 0.01 5 ______________________________________
Wines produced from Labrusca hybrid grapes and French hybrid grapes can have good storage qualities and other attributes which make them a desirable product. The problem to which the present invention is directed is the production of Labrusca grape wines of lower LFI values and the production of Labrusca hybrid and French hybrid grape wines of lower flavour, while retaining the attributes of such wines, and thereby overcome the prior art problems mentioned above.